It can be any Energy and any Pokmon, regardless of their type, which is quite nice because a lot of similar cards from the past restricted what type of Energy you could attach or what type of Pokmon you could attach it to
Its companion restriction reshaped deckbuilding across formats to the point where its influence eventually led to bans in competitive environments like Modern and Pioneer
Personally, I prefer more aggressive gameplay
Mana Rocks: Boros Cluestone, Commander's Sphere, and Mind Stone are all serving as early ramp and later card draw
This card doesnt just promise raw might it delivers, making it a top choice for players who want to pack some serious punch into their decks
Depending on the format, you may not have the strongest counterspells for everything, but good ones for specific cards